Residual Stress Measurement & Analysis
When any object is formed through cold working, there is the possibility for the development of residual stresses. These stresses are not visible, but can still decrease the total strength of the material. Therefore, it is necessary to establish means by which the residual stresses can be measured, and even predicted.
There are currently many techniques that can be used to measure the residual stresses in materials, such as the hole drilling method, and the slit cutting method. These methods however are destructive and so require samples to be made which means more time and money. There are non-destructive methods however, such as X-Ray Diffraction.
More information about residual stresses can be seen at the Residual Stress Summit 2005 webpage.
As far as predicting residual stresses, after some assumptions are made, there is the possibility of analytically calculating the final state of stress. This process can be seen under the Analytical Calculation pdf. The use of commercial numerical codes can also be employed, such as Abaqus, to develop a prediction of residual stress.